Transcript for US Mother's Heartbreaking Message on Terrorist Slaying of Son

chilling story from Iraq. We expect to hear from pes about this sometime today. The video is so graphic. Of course, we're not going to show it but it does appear to be the execution of American journalist James Foley by Isis. ABC news chief investigative correspondent Brian Ross tracks it and joins us. Reporter: The U.S. Government has not con fired the authenticity of have video but the barbaric scenes leave little doubt about what happened. Too disturbing for us to broadcast. Until the end, Jim Foley's parents never gave up hope he would return safely. But this morning, that hope has turned to grief and to pride. In a message posted overnight on Facebook, his mother, Diane said "We have never been prouder of our son Jim. He gave his life trying to expose the world to the suffering of the Syrian people." This is a tragedy which is beyond imagining. There are no words to describe this kind of inhumanity. Reporter: Foley disappeared in northern Syria about 21 months ago on assignment for "Global post" covering the brutality of the Syrian government against the rebels. These were clearly army positions throwing shells and heavy mortars into the heavy civilian population. Reporter: In the chilling video, posted online Tuesday, the 40-year-old photojournalist Foley is forced to kneel and is clearly coerced but still shows great dignity and courage. "I wish I could have the hope of freedom and seeing my family once again," he said "But that ship has sailed." It shows another hostage, identified in the video as American Steven soltoff, and they say the life of this American citizen, Obama, depends on your next decision. In her Facebook posting overnight Foley's mother Diane said "We implore the kidnappers to spare the lives of the remaining hostages. Like Jim, they are jnts," robin. There are more Americans out there. We are told there may be as many as two or three other Americans in Syria being held by this terror group.

This transcript has been automatically generated and may not be 100% accurate.

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